bluetooth audio inoperative iOS 9.3.1 device is connected but does not receive audio

Audio does not transfer to bluetooth device (RCU Connect) which is bluetooth device paired to Siemens Hearing Aids. This worked fine before latest update. The device shows up as connected (from power on, or after tapping connect), but audio is never routed to the device. Note that switching between built-in speaker and plugged in headphones still works as expected. I need the rcu (Siemens MiniTek).